PROJECT SUMMARY Pregnant women are at particular risk of negative outcomes from influenza and their infants face the most serious outcomes from pertussis infections. For this reason, the seasonal influenza and the Tetanus, diphtheria and pertussis (Tdap) vaccines are recommended for women during every pregnancy. However, coverage rates remain low with rates rarely exceeding 50% for either vaccine, far from the Healthy People 2020 goal of 80% coverage. The barriers to vaccine receipt among pregnant women have been well characterized, with concerns about the safety of the vaccine, lack of a provider recommendation and access to the vaccine/financial barriers to stocking the vaccine being some of the primary barriers. While there exist a variety of interventions to address these barriers in the clinical setting, both ones that focus on specific barriers (i.e. patient education) as well as multi-modal packages of interventions, the effectiveness of these interventions on maternal vaccine uptake are varied. There is a clear need for a framework that can be used to determine and apply the ?best practice? quality improvement interventions. The AFIX (Assessment, Feedback, Incentive, eXchange) model was developed by the National Immunization Program to do just that in the pediatric care setting for childhood immunizations. The model evaluates a practice?s baseline immunization rates and immunization delivery practices and compares this information between peer practices, promoting competition to improve immunization rates. Practices then select those quality improvement interventions that directly address the barriers to immunization delivery faced in their practice. In the proposed project, we will evaluate the effectiveness of AFIX-OB, our adaptation of the traditional AFIX model, for improving maternal immunization delivery in the obstetric care setting. We will first utilize in-depth interviews with patients and providers to refine the selection of evidence-based quality improvement interventions that will be offered to practices. Then we will use a cluster-randomized trial to evaluate the impact of the AFIX-OB model on maternal immunization uptake in a socio-demographically diverse set of obstetric care clinics within the Yale New Haven Health System. If efficacious the AFIX-OB framework has the potential to be widely implemented in a variety of obstetric care settings to improve vaccine uptake by supporting obstetric care providers as they address barriers at the practice, provider and patient levels.